Welcome Marc

I am also a Beijing rider, also a (long, long, ago in a faraway place) MSF instructor, and also an advocate of legal bikes / plates / licenses. By the way, I just heard another horror story from a friend who was stopped without a driving license. You definitely don't want to be doing that these days, so congrats on getting your license! Good show.

Getting a bike will be based on your budget. The cheapest I've recently seen a half-decent "A" plated bike is around 15K (including plate). There is a brand new Jialing JH600, complete with A plate, for sale for upper end 40s, all-in with taxes, etc.

You can see what's around (in terms of A plates) by heading to 58.com (I've filtered a search for you with an "A" plate criterion)

Cheers and, again, welcome!
Richard